Screening of bacteria to produce polyhydroxyalkanoates from xylose

Abstract

Although xylose is a major constituent of lignocellulosic feedstock and the second most abundant sugar in nature, only 22% of 3,152 screened bacterial isolates showed significant growth in xylose in 24 h. Of those 684, only 24% accumulated polyhydroxyalkanoates after 72 h. A mangrove isolate, identified as Bacillus sp. MA3.3, yielded the best results in literature thus far for Gram-positive strains in experiments with glucose and xylose as the sole carbon source. When glucose or xylose were supplied, poly-3-hydroxybutyrate (PHB) contents of cell dry weight were, respectively, 62 and 64%, PHB yield 0.25 and 0.24 g g -1 and PHB productivity (P PHB ) 0.10 and 0.06 g l -1 h -1 . This 40% P PHB difference may be related to the theoretical ATP production per 3-hydroxybutyrate (3HB) monomer calculated as 3 mol mol -1 for xylose, less than half of the ATP/ 3HB produced from glucose (7 mol mol -1 ). In PHB production using sugar mixtures, all parameters were strongly reduced due to carbon catabolite repression. PHB production using Gram-positive strains is particularly interesting for medical applications because these bacteria do not produce lipopolysaccharide endotoxins which can induce immunogenic reactions. Moreover, the combination of inexpensive substrates and products of more value may lead to the economical sustainability of industrial PHB production.

Role of <i>CcpA</i> in Polyhydroxybutyrate Biosynthesis in a Newly Isolated <i>Bacillus</i> sp. MA3.3

“…MSL7 ⌬ CcpA (Kan r ) is a derivative of the soil-isolated Bacillus sp. MA3.3 [Lopes et al, 2009], and both were cultivated in nutrient broth at 30 ° C and 200 rev ؒ min -1 . M9 medium [Sambrook et al, 1989] containing single sugar (2 g ؒ l -1 ) or sugar mixtures (1 g ؒ l -1 of each) was used in growth experiments.…”

“…In a previous screening for PHB-producing bacteria using inexpensive substrates, a mangrove soil-isolated Bacillus sp. MA3.3, closely related to B. megaterium , was isolated and reached promising results on PHB accumulation [Lopes et al, 2009]. However, when it grows in sugars usually found in lignocellulosic hydrolysates, glucose exerts a strong catabolite repression over xylose and arabinose.…”

Aproveitamento de torta do tabaco gerado na produção de biodiesel para a obtenção de bioplástico

“…Fontes de carbono purificadas, como glicose, sacarose, maltose, entre outras, podem representar mais de 30% do custo total de todo o processo produtivo (LOPES et al, 2009;SERAFIM et al, 2008). Dessa maneira, tem se buscado substratos que possuam baixo valor, mas que mantenham a taxa de produção muito próxima ou superior das obtidas com fontes de carbono convencionais (PAL et al, 2009).…”

Seleção de genes codificadores de PHA sintases para a construção de recombinantes em Burkholderia sacchari e Pseudomonas sp e avaliação da produção de polihidroxialcanoatos com diferentes composições monoméricas.

“…O interesse comercial por este polímero vem aumentando, no país graças à possibilidade de produzi-los a partir de fontes de carbono renováveis pela agricultura, como a sacarose, glicose, xilose e derivados do bagaço de cana-de-açúcar entre outros (HOLMES, 1985B;LOPES et al, 2009;LOPES et al, 2011;SILVA et al, 200 (GOMEZ, 2000b;SILVA et al, 2007). A busca foi direcionada a microrganismos capazes de crescer e acumular PHA em produtos da agricultura, resíduos industriais ou produtos químicos com potencial para gerar novos materiais (BUFFONI, 2006;MENDONÇA et al, submetido;SILVA et al, 2007 ).…”